Most vehicles have rigid roof structures that permanently extend over and cover the passenger compartment. Manufacturers also provide a variety of designs that offer the vehicle operator the opportunity to partially or completely uncover the passenger compartment. Sunroofs and moonroofs are some of the simplest designs and offer the opportunity to open a portion of the vehicle roof for increased airflow. More complicated designs allow the entire roof structure to be retracted and stored behind the passenger compartment.
Retractable roof systems generally fall into two categories. The most common type of retractable roof design is a convertible soft top or roof. These designs include an articulating structural framework with a flexible cloth or plastic outer skin. In an extended position, the front end of the articulating framework connects to a header above the vehicle windshield and the outer skin extends over the passenger compartment. When retracted, the articulating mechanism, along with the outer skin, folds into a compact shape. While convertible soft tops offer the choice between a covered or uncovered passenger compartment, they also suffer from several disadvantages in comparison to traditional rigid roof structures. Vehicles with soft tops are typically less well sealed against the elements and are somewhat noisy. They are also less resistant to break-in attempts and have a less finished interior appearance.
The other retractable roof design is a retractable or folding hardtop roof system. Retractable hardtops consist of one or more rigid roof elements that are mechanically articulated such that they can be repositioned into a storage area behind the passenger compartment. Because the retractable hardtop consists of rigid sections, the system can provide a much closer approximation of a traditional rigid roof structure. In the extended position, a retractable hardtop securely covers and seals the passenger compartment, giving the appearance of a permanent roof. A retractable hardtop does a significantly better job of sealing the passenger compartment, reducing noise, and preventing break-ins. However, the retraction and storage of the hardtop presents significant mechanical challenges. Typically, when the retractable hardtop is in the retracted position, it resides in the portion of the vehicle traditionally provided for storage, such as the vehicle's trunk. While the storage space may be completely usable when the hardtop is in the extended position, most consumers prefer not to sacrifice the use of the storage position when the roof is retracted. There is generally a tradeoff between storage efficiency and mechanical complexity.
Most modern retractable hardtop designs consist of two or more articulated sections that are automatically folded or stacked in the storage area. In one design, referred to as a “clamshell” design, the roof structure is divided into a front section and a rear section. The front and rear sections are pivotally interconnected and the rear section is pivotally connected to a support structure behind the passenger compartment. Examples of clamshell type retractable hardtop designs are shown in U.S. Pat. Nos. 6,271,104 to Neubrand, and 5,785,375 to Alexander et al.
In a clamshell design, the front and rear sections may both be the to have an inner and an outer surface, with the outer surfaces cooperating to form the outer surface of the roof structure when in the extended position. When retracted, the front section folds so as to bring the inner surface of the front section towards the inner surface of the rear section, and both sections are together positioned into the storage area. Often, the deck lid of the vehicle articulates into an out-of-the-way position to allow the hardtop sections to move into a position in the trunk. The deck lid is then repositioned to cover the pair of roof sections. In most designs, the front and rear sections both have generally convex outer surfaces and concave inner surfaces. Therefore, when the inner surfaces are folded towards one anther, the concave shapes cause there to be a significant distance between the mid-portions of the folded front and rear sections. Consequently, clamshell designs do not store as compactly as some other designs. Their advantage is that they are significantly less complex than most other designs. Reduced complexity not only reduces manufacturing costs, but also improves reliability of the system. Clamshell designs also have better structural integrity than some other designs.
An alternative design, which provides improved storage efficiency, may be referred to as a “stacking” design. Again, the roof is divided into two or more sections. However, when the hardtop is retracted, the roof sections are stacked such that the inner surface of one section is adjacent to the outer surface of another section. Because each section typically has a concave inner surface and a convex outer surface, placing the inner surface of one section next to the outer surface of another often results in more efficient space utilization. Examples of stacking retractable hardtop designs are shown in U.S. Pat. Nos. 6,336,673 to Rothe et al., 6,318,793 to Rapin et al., 6,053,560 to Rothe, and 5,979,970 to Rothe et al. As will be clear to those of skill in the art, stacking designs require significantly more complex articulation mechanisms than clamshell designs. This increased complexity leads to increased costs, reduced reliability, and reduced structural integrity.